For the in-text citation it works like for the bibliography.If there is no sort section, you can just add one (after citation, before layout).Something like this (adapt to the macros in your style, of course) should work: <sort> <key macro="year-date"/> <key macro="author-short"/> </sort>

You need to check the name of the macro in the style you're using. "The English Harvard" doesn't tell us which one you were using, so damnation picked the most common macro name, but it could well be different, e.g. issued-date etc.

Add <key variable="citation-number"/> as a third sort key to sort items by the same author in the same year by order of appearance (you could also use another variable if you like). Currently it is sorting them by the order you entered them in the citation (i.e., not sorting them in any way after author and year are considered).